title: Angiotensin II regulates islet microcirculation and insulin secretion in mice.
abstract: OBJECTIVE
  Angiotensin II causes potent increases in systemic and local pressure through its vasoconstrictive effect. Despite the importance of angiotensin II for local blood flow regulation, whether angiotensin II regulates the pancreatic islet microcirculation remains incompletely understood. We hypothesized that angiotensin II directly regulates the pancreatic islet microcirculation and thereby regulates insulin secretion. The aims of this study were to develop a new technique to visualize pancreatic islet hemodynamic changes in vivo and to analyze changes in islet circulation induced by angiotensin II or an angiotensin type 1 receptor blocker.
  
  
  METHODS
  Using an in vivo imaging method, we observed the pancreatic islet microcirculation. Various doses of angiotensin II or an angiotensin type 1 receptor blocker were injected intravenously, and changes in islet microcirculation were observed. Glucose-stimulated insulin secretion from the pancreas was measured from the hepatic portal vein.
  
  
  RESULTS
  We identified islet microcirculation using a fluorescent dye. Angiotensin II significantly induced blood vessel contraction in the islets in a dose-dependent manner. In contrast, the angiotensin type 1 receptor blocker induced vasodilation. Glucose-stimulated insulin secretion was decreased by angiotensin II infusion.
  
  
  CONCLUSIONS
  These results show that angiotensin II is involved in the regulation of pancreatic islet microcirculation and insulin secretion.
authors.affiliation: Department of Nephrology and Hypertension, Kawasaki Medical School, Kurashiki, Okayama, Japan.
authors.forename: Chieko
authors.initials: C
authors.lastname: Ihoriya
authors.forename: Minoru
authors.initials: M
authors.lastname: Satoh
authors.forename: Atsunori
authors.initials: A
authors.lastname: Kuwabara
authors.forename: Tamaki
authors.initials: T
authors.lastname: Sasaki
authors.forename: Naoki
authors.initials: N
authors.lastname: Kashihara
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D000818:Animals; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000098:blood supply / Q000378:metabolism; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D007328:Insulin; D014662:Vasoconstrictor Agents; D000804:Angiotensin II
keywords: angiotensin II; angiotensin type 1 receptor blocker; in vivo imaging; insulin secretion; islet; microcirculation